dinosaur

American  

[dahy-nuh-sawr] / ˈdaɪ nəˌsɔr /

noun

1. any chiefly terrestrial, herbivorous or carnivorous reptile of the extinct orders Saurischia and Ornithischia, from the Mesozoic Era, certain species of which are the largest known land animals.

2. something that is unwieldy in size, anachronistically outmoded, or unable to adapt to change.

   The old steel mill was a dinosaur that cost the company millions to operate.

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dinosaur British  

/ ˈdaɪnəˌsɔː /

noun

1. any extinct terrestrial reptile of the orders Saurischia and Ornithischia, many of which were of gigantic size and abundant in the Mesozoic era See also saurischian ornithischian Compare pterosaur plesiosaur

2. a person or thing that is considered to be out of date

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Other Word Forms

• dinosaurian adjective

Etymology

Origin of dinosaur

< New Latin Dinosaurus (1841), originally a genus name. See dino-, -saur

Explanation

If you've ever seen Jurassic Park, you know that dinosaurs were large reptilian creatures that walked the earth during the Mesozoic era that ran from 245 million to 68 million years ago and included the Triassic, Jurassic, and Cretaceous periods. The ancient Greeks had no knowledge of dinosaurs that we know of, but they unknowingly contributed to the word dinosaur. It was cobbled together in 1841 by British scientist Sir Richard Own, using the words deinos, meaning "terrible" and sauros meaning "lizard." All are gone—at least in their original form, although it is thought they simply evolved into other, present-day animals. The word dinosaur is often used for someone who is old-fashioned or unable to adapt to modern times.

Example Sentences

The fossil belonged to a carnivorous dinosaur species that lived more than three times earlier than Tyrannosaurus Rex.

From Science Daily • Apr. 15, 2026

The dinosaur had large cheekbones, a broad braincase, and likely a short, deep snout.

From Science Daily • Apr. 15, 2026

After years of analysis, the team determined that this dinosaur belonged to Herrerasauria, one of the earliest groups of carnivorous dinosaurs.

From Science Daily • Apr. 15, 2026

“Anne Hathaway being in it was what initially interested me . . . and then the reveal of the dinosaur aspect got my full attention.”

From Salon • Apr. 12, 2026

“Missing books? Silly dinosaur video games? Money wasted on talking statues and holograms and secret panels in bookcases that could’ve been more wisely spent on extra copies of popular children’s books?”

From "Mr. Lemoncello's Library Olympics" by Chris Grabenstein

Related Words

• antiquated
• archaic
• out-of-date
• outmoded